The invention relates to an optical disk apparatus for enabling the use of a compact disc such as a CD-ROM or the like and a cartridge enclosed medium with a motor hub such as a magneto-optical disk or the like by one apparatus and, more particularly, to an optical disk apparatus which can switch a control of a spindle motor to a constant angular velocity control (CAV control) and a constant linear velocity control (CLV control).
A compact disc (CD) has developed remarkedly over the past decade from its original audio utilization to its present use at the forefront of the multimedia frenzy. Particularly, in recent years, a personal computer containing a compact disc read only memory (hereinafter, simply referred to as a "CD-ROM") has rapidly spread. It is regarded that a CD player for reproducing a CD-ROM has been established as a third type of storage file device, the first two types of storage devices being a floppy disk drive (FDD) and a hard disk drive (HDD). On the other hand, utilization of a rewritable type optical disk apparatus using a magneto-optical disk enclosed in a cartridge is also gradually increasing due to advantages such as its large capacity and its removability. The use of such a rewritable optical disk apparatus is also being progressed as a file device using a magneto-optical disk cartridge (MO cartridge) of either 3.5 or 5 inches according to the ISO.
In a device using such a conventional optical disk media, however, an exclusive-use drive exists for each kind of the optical disk media such as CD-ROM or MO cartridge. Therefore, when the user wants to use both of the CD-ROM and the MO cartridge, both a CD player and an MO drive have to be separately prepared. Particularly, in recent years, in many cases, the CD player or MO drive is built into the apparatus' main body as a peripheral device of a personal computer. In such a case, it is difficult in terms of the space to build two devices and there is an inconvenience such that only either one of the two devices can be built into the apparatus' main body. Further, as society moves towards a full-scale multimedia age, the CD player, will not be limited to a function as simple as the reproducing apparatus of today's CD-ROM, but will necessarily employ a rewriting function which has already been realized in the MO drive. With regard to the MO drive, on the other hand, it is not limited to use as a simple file device but it is strongly demanded that the MO drive can cope with a CD-ROM, a video CD, and the like which are provided as a part of the multimedia. Particularly, when considering the rapid spread of the MO drive, it is an indispensable condition to make it possible to fetch CD resources provided in the field of a personal computer which is rapidly being spread. In the CD player, in addition to a conventional CD-DA for music and a CD-ROM for reproducing dictionary data, an image data program, and the like, the edition and storage of a large capacity of data using those media simultaneously become the necessary conditions. On the other hand, the MO drive using the readable, writable, and further removable MO cartridge having a large capacity according to the ISO is also a device that is indispensable for processes of a large amount of data which is provided by the CD-ROM or the like.